This astonishing documentary, nearly five years in the making, deserves to be
considered one of the most exceptional achievements of BBC Bristol's highly
accomplished Natural History Unit, tackling a subject that makes up seven tenths
of the Earth's surface and yet which is, in parts, less well-explored than the
surface of the moon. As the BBC's pre-publicity was anxious to point out, the
open ocean presents challenges for the natural history filmmaker beyond anything
on land - its very vastness means that finding your subject can be a daunting
task, and many of the series' most striking sequences were the result of weeks,
months or even years of patient waiting for shots that would in the end take up,
at most, just a few minutes of screen time.

Though David Attenborough lent his voice to the series and wrote much of the
narration, he doesn't appear on screen, and The Blue Planet doesn't belong in
the epic 'Life' series that he begun with Life on Earth (BBC, 1979), but is instead a precursor to the similarly ambitious Planet Earth (BBC, 2006), overseen by producer Alastair Fothergill.

With a suitably magisterial score by George Fenton, the series offered a
feast of enrapturing images: killer whales playing a gruesome game of
catch, tossing captured seals dozens of feet into the air; emperor penguins,
wary of the threat of ferocious leopard seals, launching themselves on to the
ice like missiles; a blue whale and her calf; carnivorous corals; bizarre and
beautiful organisms, translucent and illuminated against the black of the deep
ocean like creatures from the brush of the surrealist Joan Míro; the predatory
orgy following migrating sardines off South Africa's coast (in one of several
firsts, The Blue Planet's cameramen captured a previously unseen behaviour, as
dolphins, working in packs, release air bubbles to marshal the sardines into ever
tighter 'bait balls' before gorging themselves on their helpless prey).

The series' most dramatic sequence followed the relentless pursuit of a
migrating grey whale and her calf by a pod of killer whales. Over many miles,
the hunters keep up their chase, forcing the mother whale to flee at a pace that
her calf cannot maintain for long. Eventually, she is forced to rest and the
ruthless killers move in, forcing themselves between mother and calf. In the
end, the young whale's carcass hangs limp; the killers have eaten only the lower
jaw.